Indicator tube utilizing a barrier electrode around each of the indicator units to which one of two voltages may be applied

ABSTRACT

A flat type multi-figure numeric or alpha numeric display device employing a cold cathode gas discharge with a barrier anode associated with each figure. Each figure of the device is composed of segmented electrodes located in a co-planar arrangement. Segments are selectively energized by the driver logic to display required figures, in combination with an electrode in the same plane which selectively may function as either an anode or as an ion barrier.

United States Patent. 1191 Yanagisawa [4 1 June 5, 1973 [54] INDICATOR TUBE UTILIZING A [56] References Cited BARRIER ELECTRODE AROUND UNITED STATES PATENTS EACH OF THE INDICATOR UNITS TO 1 3,327,153 6/1967 Bickmire et al. ..313/109.5 VOLTAGES 3,327,154 6/1967 Bowerman ...313/109.5 3,652,891 3/1972 Janning "313/1095 [75] Inventor: Yuzuru Yanagisawa, Fuzisawa-shi,

Kanagawa-ken Japan Primary Examiner-Roy Lake Assistant Examiner-Siegfried H. Grimm [73] Asslgnee: Sony Corporatlon Tokyo Japan Attorney-Carlton Hill, Benjamin H. Sherman, [22] Filed: Sept. 15, 1971 Charles F. Meroni et al.

[21] Appl. No.: 180,727 [57] ABSTRACT A flat type multi-figure numeric or alpha numeric dis- [30] Fore'gn Apphcat'on Pnomy Data play device employing a cold cathode gas discharge Sept. 18, 1970 Japan ..45 s1750 with a barrier anode associated with each figufe- Each figure of the device-is composed of segmented elec- 52 US. Cl. ..313/109.5, 313/210, 313/217, tmdes located in a cO-Planar arrangement Segments 315/169 R 315/169 TV 340/324 R are selectively energized by the driver logic to display 340/344: required figures, in combination with an electrode in 511 1111.01. .5 .1101 61/66, HOlk 7/04 the Same Plane which seleflively may as [58] Field 61 Search ..313/109.5, 210, 217; anode as 315/846, 169 R, 169 TV; 340/324 R, 344

7 Claims, 7 Drawing Figures PATENTED JUN 5 SHEET 1 OF 3 PRIOR ART INVENTOR. 712 we a fiA/A G/sA WA ATTORNEY V PATENTEDJUN 5191s SHEET 2 OF 3 INVENTOR.

fizz/Ru XWA e/sAn/A @Mfl PATENTED 75 737, 707

sum 3 OF 3 INVENTOR. ku X4/V/1G/5An/A BY M ATTORNEY INDICATOR TUBE UTILIZING A BARRIER ELECTRODE AROUND EACH OF THE INDICATOR UNITS TO WHICH ONE OF TWO VOLTAGES MAY BE APPLIED CROSS REFERENCE TO RELATED APPLICATIONS The present invention is an improvement over the invention disclosed in pending applications, Ser. No. 128,888, filed Mar. 29, 1971; Ser. No. 155,555, filed June 22, 1971; and Ser. No. 172,855, filed Aug. 18, 1971, all of which are assigned to the same assignee as the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to gaseous glow indicator tubes and particularly to that type of indicator tube in which a number ofindicator units are contained within a sealed envelope and which have one or more anodes for each indicator unit and a number of cathodes for each indicator unit, the anodes being energized on a time sequential basis, and selected cathodes of each indicator unit being connected on a time sharing basis to a potential source which is negative with respect to the anode potential source.

2. Description of the Prior Art Gaseous glow indicator tubes which include a plurality of indicator units mounted inside a transparent envelope and which are utilized for displaying numerals, symbols, letters, or the like, have been commercially available. For example, such indicators have been used with electronic counters and various other indicating means. One example of such indicators are the socalled Nixie" tubes in which an anode electrode and a plurality of cathode electrodes are aligned in a stack one above the other such that selected cathode elements may be energized so that an observer sees a selected numeral or letter. Other glow indicator tubes utilize cathode segments mounted in a common plane with an anode in the form of a wire screen or mesh mounted in a second plane and which when various cathode segments are energized at the same time that the corresponding anode is energized the unit will glow.

Such prior art indicator tubes utilized a separate lead for each of the anodes, or alternatively provide separate leads for each of the cathode segments. This resulted in indicator tubes with a very large number of leads and limited the minimum size of the unit as well as requiring many electrical connections to be made to each of the units.

In US. Pat. No. 3,588,571 an indicator tube is described in which each of the cathode electrodes or a plurality of indicating units are commonly connected to each other by a single lead. This eliminates the necessity for a number of cathode leads corresponding to the number of cathodes in the entire indicator tube. Glow indicator tubes are known which utilize cathode segments mounted in a common plane and are disclosed, for example, in US. Pat. No. 3,418,509.

SUMMARY OF THE INVENTION The present invention comprises a novel indicator tube in which a plurality of indicator units are formed in a common plane, each indicating unit including a plurality of cathode segments and one or more electrodes formed in the same plane. Each indicator unit is isolated from other indicator units by having the electrode surround each indicator unit respectively and by applying a potential bias to cause it to function as an ion barrier.

Similarly located cathode segments are electrically connected together and in which anode segments for each indicator unit are time sequentially energized such that a particular indicating unit which has its anode energized produces an indication. The barrier electrode also functions as an anode when a higher potential bias is applied thereto. Thus the electrode sur rounding each indicating unit acts as a barrier, when supplied with a positive potential sufficient to prevent unwanted energization of an adjacent indicating unit but not sufficient in itself to cause energization of any cathode segments in its own associated indicating unit.

Accordingly, one of the objects of this invention is to provide an improved indicator tube in which there is a plurality of indicator units eachincluding a plurality of cathode segments, at least one electrode, which acts either as an anode or as a barrier, depending on the voltage applied thereto. Each barrier or anode surrounds the cathode segments of its associated indicator unit.

A further object of the present invention is to provide a gaseous glow indicator device having a base plate, a plurality of indicator units formed in a single plane on said base plate, each indicator unit including a plurality of cathode segments, at least one anode and barrier electrode surrounding each indicator unit, means for applying a first voltage to the electrodes to prevent undesired accidental actuation of indicator units, and means to apply a second voltage to at least one of the electrodes to actuate the indicating unit corresponding thereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic illustration of a fragmental portion of an indicator tube;

FIG. 2 is a plan view showing only two of the electrodes of the indicator unit of FIG. 1 and showing the energization circuit for the cathode segments and the anode electrodes;

FIG. 3 is a diagrammatic sectional view of a portion of an indicator tube of this invention;

FIG. 4 is a plan view of the tube exemplified by FIG. 3; and

FIGS. 5, 6 and 7 are wave pulse diagrams explaining the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is schematically illustrated a conventional flat-type indicator tube for displaying letters, numerals, symbols or the like. As shown in the figure, this indicator tube includes an insulating plate 1 forming a part of an envelope 2, on which plate are formed a plurality of indicator units A,, A etc., each consisting of a plurality of cathode segments E to E arranged in a figure 8 configuration and anode segments P P and P associated with the cathode segments as illustrated in FIG. 2.

For reducing the number of leads from the envelope 2, corresponding electrodes E to E of each of the indicator units A,, A etc. are connected together in the envelope and are grounded or connected to a predetermined negative voltage source through switches S to S,,. The anode segments P, to P of the respective indicator units are connected to switches K,, K etc.

The indicator units A,, A etc are energized on a time sequential basis for providing a display. That is, in the case of dispiaying a number, for example, 1.8 with the indicator units A, and A,,, the switches S, to S are closed first to ground the cathode segments E 13 and E and the switch K, is closed to supply an anode voltage to the anode segments P, to P of the indicator unit A,, by which the cathode segments E E and E,, are lighted to display 1..

Then, the switches S, to S and K, are opened and the switch K, is closed and, at the same time, the switches, 5,, S and S to S are closed, by which the cathode segments E, to E of the indicator unit A are lighted to display 8. By alternate change-over of the switches, 1. and 8 are alternately displayed with the indicator units A, and A and, by increasing the switching speed, 1. and 8 can be dispiayed as if they are simultaneously displayed as 1.8 at all times.

However, such time sequential energization of the indicator units introduces the possibility of a wrong message display. Namely, an inert gas such as neon or argon sealed in the envelope 2 is ionized by the repetition of glow discharge for a certain period of time and the ionized ions are scattered in the envelope 2, by which a discharge initiating voltage between the anode and cathode segments is lowered and glow discharge readily occurs. Accordingly, in the case of causing the indicator unit A, to display 1., glow discharge is caused between the anode electrodes P, to P of the indicator unit A, and the cathode segments E E and E of the other indicator units A A A,,, to provide a wrong display 1. l. 1 In connection with the display of 8, too, a similar wrong display 8 8 8 is also likely to occur.

To avoid such a wrong message display, a common barrier electrode C is formed on the insulating plate 1 surrounding the indicator units A,, A etc. as shown in FIG. 2. The barrier electrode C is supplied with a fixed positive voltage such, for example, as about 100 volts which is lower than a discharge supporting'voltage, such as 150 to 200 volts, between the anode segments P, to P and the cathode segments E, to E and does not cause a potential difference between the cathodes and the anode segments to exceed the discharge initiating voltage therebetween. Thus, an accidental discharge is prevented by the barrier field established by the barrier electrode C. 1

This invention provides a flat-type indicator tube which is provided with barrier electrodes but does not require leads therefor and in which more cathode segments may be employed than those employed in a simple figure 8 configuration type tube, and thus it is possible to display more letters, symbols or the like than those obtainable with the prior type tube.

Referring now to FIGS. 3 and 4, one example of this invention will hereinbelow be described as being applied to a discharge type indicator tube such as above described in connection with FIGS. 1 and 2.

In accordance with the present invention, a plurality of indicator units A,, A etc. each consisting of a plurality of cathode segments E, to E, arranged in the form of, for example, a cross in a square, are formed on a common insulating base plate 4 which forms a part of an envelope 3 and independent combined anode and barrier electrodes 8,, 8,, etc. are formed on the insulating base plate 4 such that each electrode surrounds each indicator unit, as depicted in FIG. 4. Only selected ones of the electrodes 8,, 8,, etc., corresponding to the indicator units to be energized, are supplied with a voltage higher than a discharge initiating voltage and the selected electrodes are thereby caused to serve as anode electrodes, while the electrodes 3,, B etc. corresponding to the indicator units to be held inactive, are supplied with a voltage which does not cause discharge between the electrodes and the cathode segments of the undischarged indicator units but is high enough to prevent ionized ions from flowing into the inactive indicator units from the discharged ones.

In this case, the anode voltage is about 160V and the ion barrier voltage is 40 to 120V, preferably about V.

The anode and ion barrier voltages may be selectively impressed on the electrodes 3, B etc. by means of a circuit such, for example, as shown in FIG. 4. Namely, as depicted, first switching transistors T,, T,, etc. are connected between the independent combined anode and barrier electrodes 8,, 3,, etc. and an anode power source 5 of, for example, about 160V respectively and these switching transistors T,, T,, etc are switched on and off to selectively apply an anode voltage to the electrodes 8,, 13,, etc. Further, impedance elements D,, D etc. are connected between the electrodes B,, 8,, etc. and an ion barrier power source 6 of, for example, about V respectively and when the switching transistors T,, T etc. are in the off state, an ion barrier voltage of 1 10V is supplied to the electrodes 8,, B etc. corresponding to the switching'transistors held non-conductive.

While, corresponding ones of the cathode segments E, to E,,, of the indicator units A,, A etc. are connected together and their leads are led out from the envelope 3 and grounded through second switching transistors T, to T,,,'. When the switching transistors T, to T,,, are in the on state, the cathode segments E, to E, connected thereto are supplied with ground potential. When the transistors T, to T,,,' are in the off state, a voltage of, for example, 45V derived from a voltage dividing circuit made up of resistors R, to R, is applied to the cathode segments E, to E,,, through diodes d, to d,,, respectively.

Further, input terminals r,, t,, etc. of the first switching transistors T,, T etc. are supplied with timing pulses e,, e,, etc. such as shown in FIGS. 5 to 7 respectively. While input terminals 2, to t,,,' of the second switching transistors T, to T are supplied with decoding signals respectively.

With the above arrangement, in the case of displaying a number 1.8, the timing pulse e, of FIG. 5 is sup plied to the input terminal t, of the first switching transistor T, to turn it on to apply the anode voltage of V to the combined anode and barrier electrode B, of the indicator unit A,. While the decoding signal is supplied to the input terminals t t and t, of the second switching transistors T T and T, to turn them on to apply ground potential to the cathode segments E E and E-,, by which discharge is caused between the anode electrode B, and the cathode segments E,,, E, and E, to light the latter, thus displaying 1." At this time, the switching transistors T, to T.,, T,,', T, and T,,,' connected to the other cathode segments E, to E 15,, E and E, are in the off state, so that these cathode segments are supplied with a positive voltage of 45V to hold the potential difference between each of these cathode segments and the anode electrode 8 of the indicator unit A lower than the discharge initiating voltage therebetween, thus preventing accidental discharge.

While in the other indicator units A A etc. their combined anode and barrier electrodes B B etc. are supplied with the ion barrier voltage of 110V through the impedance elements D D etc. respectively because of non-conduction of the switching transistors T T etc. connected to the electrodes B B etc. so that an ion barrier field is produced based on the ion barrier voltage to prevent scattering of ionized ions, thus avoiding accidental discharge in the indicator units A A etc.

Then, the timing pulse 2 depicted in FIG. 6 is supplied to the first switching transistor T and the decoding signal is applied to the second switching transistors T T T T T T and T by which the indicator unit A is caused to display 8. Also in this case, accidental discharge is similarly prevented. Thereafter, 1. and 8 are alternately displayed to provide a display of the number 1.8" without fail.

With the present invention above described, the independent electrodes 8,, B etc. are disposed around the indicator units A,, A etc. respectively and are selectively supplied with the anode voltage and the ion barrier voltage, thereby to ensure avoidance ofa wrong message display. Accordingly, as compared with the indicator tube shown in FIGS. 1 and 2, the tube of this invention is simple in the electrode structure and the number of leads led out from the envelope is small.

Since no anode electrode is incorporated in the pattern of the cathode segments of the indicator unit, it is possible to make up the indicator unit with many cathode segments which are arranged in the form of, for example, a cross in a square for displaying alphabets.

In the foregoing example the cathode segments E to E and the electrodes B B etc. are aligned in the same plane on the insulating base plate 4, but the electrodes B B etc. can be disposed above the cathode segments E to E Although the present invention has been described as being applied to the discharge type indicator tube, the invention is applicable to, for example, a fluorescent indicator tube. Namely, a plurality of indicator units, each consisting of anode segments coated with a phosphor material and arranged in a predetermined pattern, are aligned on a common insulating base plate; independent grids are disposed corresponding to the indicator units respectively; a filament is disposed above the indicator units; the grid corresponding to the indicator unit to be energized is supplied with a predetermined voltage to case impingement of electrons from the filament onto the anodes of the indicator unit energized; and those grids corresponding to the indicator units to be held inactive are supplied with a control voltage more negative than the aforementioned predetermined voltage to prevent impingement of the electrons from the filament onto the anodes of the indicator units. Thus, a wrong message display can be avoided by selective application of the control voltage to the grids.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

I claim as my invention:

1. An indicator tube comprising:

a planar base plate of an insulating material;

a plurality of indicator units aligned on one side of the planar base plate, each of the indicator units comprising a plurality of cathode segments arranged in a predetermined configuration;

a plurality of barrier electrodes formed on the same side of the planar base plate and with one of said barrier electrodes surrounding each one of said indicator units, respectively;

a transparent sealed envelope enclosing said planar base plate; and

an ionizing gas in said sealed envelope.

2. An indicator tube according to claim 1 in which each of said barrier electrodes is selectively energized with one voltage which causes its associated indicator unit to glow when certain cathode segments are energized while other of said barrier electrodes are energized with a lower voltage to create an ion barrier around their associated indicator units to prevent glow.

3. An indicator tube according to claim 1, wherein corresponding ones of said plurality of cathode segments of each of said indicator units are electrically connected together, means for selectively applying a voltage to said cathode segments, a first positive voltage source connected one at a time to said plurality of barrier electrodes on a time sequential basis to energize the cathode segments of each indicator unit as said first voltage source is connected to the associated barrier electrode, and a second positive voltage source having a lower potential than said first voltage source connected to all of the barrier electrodes of said other indicator units than the one to which said first voltage source is connected to prevent energization of the associated cathode segments of said indicator units.

4. An indicator unit according to claim 3 comprising a plurality of cathode leads corresponding in number to the number of cathode segments of a single indicator unit, each one of said cathode leads connected to said corresponding ones of said plurality of cathode segments of each of said indicator units, and said means for selectively applying a voltage to said cathode segments connecting certain ones of said plurality of cathode leads to a source of potential which is negative with respect to both said first and second positive voltage sources to create a desired pattern on a particular indicator unit each time said barrier electrode of said particular indicator unit is connected to said first positive voltage source.

5. An indicator tube as claimed in claim 1, including a plurality of barrier leads and each one connected to a different one of said plurality of barrier electrodes.

6. An indicator tube comprising:

a base plate of an insulating material;

a plurality of indicator units aligned on one side of the base plate, each of the indicator units including a plurality of segments arranged in a predetermined configuration;

a plurality of barrier electrodes formed on said one side of the base plate and each of said barrier electrodes surrounding one of said plurality of indicator units;

a transparent envelope enclosing said base plate;

an ionizing gas in said envelope;

corresponding ones of each of said plurality of segments of each of said indicator units electrically connected together;

means for selectively applying a first voltage to said segments;

means for applying a second voltage to most of said plurality of barrier electrodes to prevent accidental actuation of the indicator units corresponding thereto; and

means for applying a third voltage to at least one of the other of said plurality of barrier electrodes to actuate the indicator unit corresponding thereto.

7. An indicator unit comprising:

a planar base plate of insulating material;

a plurality of indicator units on one side of the planar base plate;

a transparent cover sealed to said base plate and forming a chamber therewith enclosing said indicator units;

an ionizable gas within said chamber;

each of said indicator units including a plurality of cathode segments in a discrete pattern located in a single plane;

an electrode for each indicator unit which surrounds 8 the cathode segments of the indicator unit and located in the same plane as said cathode segments;

the cathode segments of each indicator unit being,

connected through leads to similarly positioned cathode segments of all indicator units;

means for time sequentially applying a bias potential to each of said electrodes sufficient to cause ionization of gas adjacent selected cathode segments of each indicator unit whose electrode is so biased when such selected cathode segments are given a decoding potential negative with respect to said bias potential;

means for sequentially connecting a decoding potential to said selected segments of each indicator tube to form a desired pattern; and

means for applying a biasing potential to those electrodes which have not received a potential sufficient to cause ionization with a potential insufficient to cause ionization but sufficient to act as an ion barrier. 

1. An indicator tube comprising: a planar base plate of an insulating material; a plurality of indicator units aligned on one side of the planar base plate, each of thE indicator units comprising a plurality of cathode segments arranged in a predetermined configuration; a plurality of barrier electrodes formed on the same side of the planar base plate and with one of said barrier electrodes surrounding each one of said indicator units, respectively; a transparent sealed envelope enclosing said planar base plate; and an ionizing gas in said sealed envelope.
 2. An indicator tube according to claim 1 in which each of said barrier electrodes is selectively energized with one voltage which causes its associated indicator unit to glow when certain cathode segments are energized while other of said barrier electrodes are energized with a lower voltage to create an ion barrier around their associated indicator units to prevent glow.
 3. An indicator tube according to claim 1, wherein corresponding ones of said plurality of cathode segments of each of said indicator units are electrically connected together, means for selectively applying a voltage to said cathode segments, a first positive voltage source connected one at a time to said plurality of barrier electrodes on a time sequential basis to energize the cathode segments of each indicator unit as said first voltage source is connected to the associated barrier electrode, and a second positive voltage source having a lower potential than said first voltage source connected to all of the barrier electrodes of said other indicator units than the one to which said first voltage source is connected to prevent energization of the associated cathode segments of said indicator units.
 4. An indicator unit according to claim 3 comprising a plurality of cathode leads corresponding in number to the number of cathode segments of a single indicator unit, each one of said cathode leads connected to said corresponding ones of said plurality of cathode segments of each of said indicator units, and said means for selectively applying a voltage to said cathode segments connecting certain ones of said plurality of cathode leads to a source of potential which is negative with respect to both said first and second positive voltage sources to create a desired pattern on a particular indicator unit each time said barrier electrode of said particular indicator unit is connected to said first positive voltage source.
 5. An indicator tube as claimed in claim 1, including a plurality of barrier leads and each one connected to a different one of said plurality of barrier electrodes.
 6. An indicator tube comprising: a base plate of an insulating material; a plurality of indicator units aligned on one side of the base plate, each of the indicator units including a plurality of segments arranged in a predetermined configuration; a plurality of barrier electrodes formed on said one side of the base plate and each of said barrier electrodes surrounding one of said plurality of indicator units; a transparent envelope enclosing said base plate; an ionizing gas in said envelope; corresponding ones of each of said plurality of segments of each of said indicator units electrically connected together; means for selectively applying a first voltage to said segments; means for applying a second voltage to most of said plurality of barrier electrodes to prevent accidental actuation of the indicator units corresponding thereto; and means for applying a third voltage to at least one of the other of said plurality of barrier electrodes to actuate the indicator unit corresponding thereto.
 7. An indicator unit comprising: a planar base plate of insulating material; a plurality of indicator units on one side of the planar base plate; a transparent cover sealed to said base plate and forming a chamber therewith enclosing said indicator units; an ionizable gas within said chamber; each of said indicator units including a plurality of cathode segments in a discrete pattern located in a single plane; an electrode for each indicator unit wHich surrounds the cathode segments of the indicator unit and located in the same plane as said cathode segments; the cathode segments of each indicator unit being connected through leads to similarly positioned cathode segments of all indicator units; means for time sequentially applying a bias potential to each of said electrodes sufficient to cause ionization of gas adjacent selected cathode segments of each indicator unit whose electrode is so biased when such selected cathode segments are given a decoding potential negative with respect to said bias potential; means for sequentially connecting a decoding potential to said selected segments of each indicator tube to form a desired pattern; and means for applying a biasing potential to those electrodes which have not received a potential sufficient to cause ionization with a potential insufficient to cause ionization but sufficient to act as an ion barrier. 